Refactor and simplify rule_group_interval_seconds (#6711)
Refactor and simplify rule_group_interval_seconds (#6711)

Signed-off-by: Julien Pivotto <df1ed88a312a603dfee9f157a90fa8f7f195ab59@inuits.eu>
prometheus/prometheus,keegancsmith/prometheus,kangwoo/prometheus,keegancsmith/prometheus,alileza/prometheus,GoogleCloudPlatform/prometheus,GoogleCloudPlatform/prometheus,GoogleCloudPlatform/prometheus,prometheus/prometheus,alileza/prometheus,alileza/prometheus,GoogleCloudPlatform/prometheus,alileza/prometheus,keegancsmith/prometheus,prometheus/prometheus,prometheus/prometheus,kangwoo/prometheus,alileza/prometheus,keegancsmith/prometheus,Gouthamve/prometheus,keegancsmith/prometheus,kangwoo/prometheus,Gouthamve/prometheus,prometheus/prometheus,Gouthamve/prometheus,Gouthamve/prometheus,kangwoo/prometheus,GoogleCloudPlatform/prometheus